Weighing scale system with weight recorder



A ril 14, 1959 J. LAULER rAL WEIGHING SCALE SYSTEM WITH WEIGHT RECORDERFiled Feb. 21, 1952 4 Sheets-Sheet 1 //O V i 60/21 IB 27 L 0/4 D CELLPLATFORM SCALE FIG.1

' INVENTORS MATTHEW 7T THORSSON BY .LOU/S JLAULER @441 ATTORNEY April1959" J. LAULER ET AL 2,882,035

WEIGI -IIN G SCALE SYSTEM WITH WEIGHT RECORDER Filed Feb. 21, 1952 4Sheets-Sheet 4 INVENTOR MATTHEW 77 THoRss N .LOUIS J. .LAULER ATTORNEYUnited States Patent WEIGHING SCALE SYSTEM WITH WEIGHT RECORDER Louis J.Lauler and Matthew T. Thorsson, Rock Island, 11]., assignors toFairbanks, Morse & (30., Chicago, Ill., a corporation of IllinoisApplication February 21, 1952, Serial No. 274,166 9 Claims. (Cl. 265-)This invention relates to weighing scales, and more particularly to aweighing scale organization embodying an electrical system for sensingscale loading and effecting weight indication and recording of scaleloads. The instant application is a continuation-in-part of ourcopending application entitled Weighing Scale System, filed November 30,1951 and bearing Serial No. 259,148, now Patent No. 2,766,981.

In general, the weighing scale organization of the present inventionincludes load support means which for example, may be a scale platformand lever system of any well known type, and strain gage load cell meanscoupled to the load support means for sensing the loading of thesupport. The load cell means herein employed is of known construction,providing an electrical network normally balanced under zero straincondition of the cell means, and producing an output voltage themagnitude and phase direction of which are directly dependent upon theextent and direction of unbalance of the network as determined in theload sensing function of the cell means, by the application of load toand load removal from the scale load support means. The load cell meanswhich in load sensing unbalance of its network produces an outputvoltage proportional to the weight of the scale loading, is included inthe electrical system of the present invention, to function as theactivating agency in such sys term. The electrical system referred to,embodies in addition to the cell means, a tare bridge network, aregulated balance bridge network including a balancing potentiometer,phase sensitive amplifier, a reversible motor in operative connection tothe balancing potentiometer and to weight indicator and recorder means,and control provisions effective for preventing weight-recordingoperation of the recorder means until the electrical system attains astable balanced condition in its scale load sensing function.

In the scale organization generally outlined above, the cell meansnormally is subjected to an initial strain due to the tare or deadweight of the load support means, which results in a cell network outputvoltage proportional thereto. Such cell voltage alone or as increased inmagnitude due to load tare weight imposed on the load support, isnullified through the tare bridge network which is made adjustable forthat purpose, so that this initial cell voltage will not interfere withthe normal weight sensing and indicating function of the system inrespect to all loads to be measured. Once the tare bridge adjustment ismade, application of load to the support means will unbalance the cellnetwork to activate the electrical system, the net cell output voltage(in the range above the initial cell voltage cancelled out by the tarebridge network) then being applied to the balance bridge network andcausing through the amplifier means, operation of the motor in theproper direction such that it actuates the balancing potentiometer inthe direction to produce an opposing voltage in the balance bridgenetwork and balance out the net cell output voltage, whereupon the2,882,035 Patented Apr. 14, I959 motor stops. Any decrease in the loadunder measure ment or its removal from the support, will effectcorresponding decrease in the net cell output voltage with resultantunbalance of voltages in the balance bridge network in the oppositedirection, and consequent reverse operation of the motor to actuate thepotentiometer in the opposite direction until the balance bridge onceagain provides an opposing voltage equal to the new net cell outputvoltage. In all cases the extent of motor operation in either direction,is a definite function of the magnitude of the net cell output voltage,while the net cell voltage is directly proportional to the weight of theload to be measured. Therefore, the extent of motor operation isproportional to the weight of the load to be measured, so that in thepresent system the motor afiords a ready instrumentality for operatingsuitable weight indicator means and for properly conditioning recordermeans to provide weight recording or printing of scale load weights.

Moreover, through regulation of the balancing characteristics of thebalance bridge network, the extent of motor operation may be related tothe Weight of the scale load to be measured, by a definite ratiopredetermined such that the motor in operating through reduction gearmeans selected in accordance with said ratio, will operate the indicatormeans to provide weight reading of the scale load weight in terms ofunits of a given weight measuring system, as pounds for example, andconcurrently therewith condition the recorder means for recording orprinting the scale load weight in terms of the same units. Although notshown herein, the present system may be readily adapted for indicatingand recording scale load weights selectively in terms of units of anyone of several different measuring systems, as by utilizing for suchpurpose the novel control provisions disclosed in the aforesaid PatentNo. 2,766,981.

The electrical system embodies in addition, an energization controlprovision for the reversible motor, which is operable selectively tocondition the motor for operation in response to load cell sensing ofscale loads, or to prevent motor operation. By this provision the motorwhen operated to set-up a weight indication on the indicator means, andto condition the recorder for weight printing, may be held in itsoperative position irrespective of a given weight, holding of the weightindication while another similar weight is applied to the weighingmechanism, and thence reconditioning the motor for operation to indicatethe new Weight without requiring return of the motor to its initialposition representative of zero scale load, whereby to reduce the timeelement in weight indications where a group of nearly similar weightsare to be measured.

' An important feature of the present invention resides in the controlprovision hereinbefore mentioned, which is adapted for sensing balancedand unbalanced conditions of the electrical system, and for preventingweight recording or printing operation of the recorder means until theelectrical system is exactly in balance. The control is embodied inphase-sensitive electronic relay network means of a character andfunction which will appear hereinafter, and is provided for the purposeabove indicated and as a means for preventing both inaccuracy in weightprinting or recording, and damage to the recorder and other elements ofthe scale system.

The foregoing and other features of the present invention, together withthe several objects and advantages thereof, will appear more fully uponconsideration of the following description of the invention as shown bythe accompanying drawings, wherein:

Fig. 1 illustrates diagrammatically, a platform scale mechanism andelectrical apparatus in operative association therewith for sensingscale loading, producing weight indications of scale loads andconditioning weight recordingmeans for producing printed or recordingsofscale load weights.

Fig. 2 is a diagram of the electrical circuit arrangement'for theelectrical apparatus "and weight printer as diagrammatically shown inFig. 1. l

"Fig. 3 is a circuit diagram like that of Fig. 2, but illustrating"a-modification in respect to the weight printer control provision ofthe circuit of Fig. 2.

Fig. 4is' a circuit diagram illustrating a modified form of scalebalance sensing device suitable for controlling weight printeroperation.

"Fig. 5 is a circuit diagram of another form of scale balance sensingdevice, and 1 Fig. 6 is a circuit diagram of yet another form of scalebalance sensing device. i a -"Referring to the drawings and first toFig. 1 thereof, the electrical system for sensing and producing weightindications of scale loads, is shown by way of example," in operativeassociation with a load support or platform scale mechanism generallyindicated at 10. Such mechanism may'be of usual or well known platformand lever construction providing an output lever 11 movable in responseto'loading and unloading of the scale platform 12.. In place of theusual mechanical balance beam provision operated from the output lever11 as through a steelyard connection, is a single strain gauge'load celldevice 14. The load cell 14 is of known construction, aridis supportedfrom a fixed support 15 and coupled to the scale output lever 11 as at16, so that its strain responsive'element is thereby directly subject todisplacement of the lever 11 consequent to loading and-unloading of thescale platform 12. As is known, the load cell 14 embodies an electricalnetwork having an input circuit supplied from a constant voltage sourcesuch as the secondary winding 18 of an alternating current supplytransformer 19, and an output circuit providing an output potential themagnitude and phase direction of which are dependent upon the extent anddirection of-unbalance of the cell network consequent to cell reactionto the loading and unloading of the scale mechanism. 'Although analternating current source of input to the cell network is here shown inthe preferred example of the invention, where it is desired a suitablesource of direct current voltage may be employed to supply the cellnetwork input.

The cell output voltage is transferred through the output side of a tarebridge network 20, the output side of a balance bridge network 22, and asuitable phase sensitive electronic amplifier 23, to the control fieldportion (see Fig. 2) of a reversible motor 24. Motor 24 serves throughsuitable reduction gearing 25, to operate a network rebalancing deviceembodied in the balance bridge 22, a weight indicator device such as adial indicator 26, and in conjunction with operation of the indicator26,-to condition printer mechanism 29 for weight recording or printingas will appear hereinafter. The device 33 represents the scale balancesensing control provision of the present invention, afiecting theprinter 29 as will be described presently. The input circuit of tarebridge '20 is supplied from a fixed source, as the transformer secondarywinding 27, while the input of balance bridge 22'is supplied fromsecondary winding 28 of transformer 19 through an electrical control 30of a nature and serving a purpose to appear. The weight sensing andweight indicating and recording function of the electrical system,together with the purpose and function of the tare and balance bridgenetworks, the bridge control 30 and balance control '33 for'printer 29,will appear from the following description of the electrical circuitportion of the system shown in greater detail by Figure 2.

Referring to Fig. 2, the electrical network of the strain gauge loadcell 14 is shown in the form of a Wheatstone bridge generally indicatedby the numeral 31, having input terminals 32 and output terminals 34.The bridge input agi fi.

terminals 32 are connected through an input circuit 35 to the-voltage--source provided b"y --the secondary -winding 18 of the supplytransformer 19, supplying a made termined fixed voltage at the networkinput terminals. It may be noted here that the load cell 14 is selectedsuch that its load responsive capacity corresponds to the load capacityof the associated platform scale mechanism 10 illustratedin Fig. 1.

One output terminal 34 of the cell network is connected by a lead 36 tothe movable element 38 of a variable resistance device or potentiometer39 providing two legs of the'tare'bridge network 20,'while the oppositeoutput terminal 34 of the cell network is connected by lead 40 to oneinput terminal 42 of a suitable phase sensitive electronic amplifier 23.

The remaining or complementary legs of the tare bridge 20 are providedby fixed resistance elements 43 and 44, the bridge providing inputterminals 46, a fixed output terminal '47 andopposite output-terminalwhich is' 'here constituted by' the movable element-38 of the bridge 'potentiomete'r' 39. The input terminals are connected through a circuit 48with a bridge inputsoilrce provided by the transformersecondarywinding'27 affording a predetermined constant voltage presentlyto be referred to. A circuit lead 50 connects the fixed output terminal47 of the tare bridge to the movable element 51'of a potentiometer 52.The potentiometer 52 provides two legs of balance bridge network 22, theopposite two-legs of which arefound in fixed resistance elements 54 and55. The bridge input terminals '56'are supplied through conductors 58and 59, with an input voltage derived from the transformersecondarywinding 28. It is to be noted that the conductor 59 includesresistance means forming the control 30 as indicatedin Fig. *1, thenature and function of which will be more fully described hereinafter.The'fixed output terminal 60 of the balance bridge is connected bycircuit 'lead'62 with the remaining input terminal 63 of theamplifier-23. The output of the amplifier is connected by the-circuit64"to the-control field winding 66of the reversible motor 24. The motor24 which may be of a well-known two-phase type, includes a main fieldwinding 68 energized from a suitable fixed voltage source, as the 110volt, 60 cycle source 69 to which the winding is connected by thecircuit 70 through normally closed manual switch 78 and a cam-controlledswitch to be described presently. -Motor 24 serves through reductiongear mechanismdiagrammatically indicated at 25, to operate the movableelement 51' of the balance bridge potentiometer 52, and atthe sametime'to operate a weight indicator 26'which ishere shown by wayofexample only, to be of a dial type, andto condition the printermechanism 29 for weight printing. The latter function will appear morefully hereinafter.

As is known in connection with strain gauge cells of the character nowindicated, the'cellne'twork output is at zero voltage under -thecondition 'of zero' strain of the cell: Inthepresent-application of theloa'd'cell to a load support such as the indicated platform mechanism(Fig. 1 the cell 'is' under an initial strain due to the tare or deadweight-of-the scale platform and associated lever mechanism'includingthe output lever 11. In a system of the character under consideration,it is desirable to eliminate such initial output voltage fromany effectupon the electrical system in" its load weight indicating function. Thismaybe done 'by balancing out such voltage through the tare bridgenetwork 20. To that end,'the balancing characteristics of the tarebridge and the bridge input voltage from the transformer secondarywinding 27 are predeterminedwith respect to the init al cell outputvoltage, or such voltage-as it maybe increased by tare weights imposedon the scale platform, so that upon adjustment of the tare bridgepotentiometer 39, the initial voltage will be effectively cancelled.Consequently, the cell voltage effective in the system beyond the anbrid e ll its h Pa te 9.? F1 9 9? Pa e? voltage which is directlyrepresentative of the loads to be measured.

In the absence of a load to be measured on the scale platform 12, thenet output voltage of the load cell will be zero since the initial cellvoltage due to the tare or dead weight of the scale mechanism and anyload tare weight on the platform, is cancelled out through the tarebridge 20. Under this condition, the motor 24 is set to position themovable element 51 of the balance bridge potentiometer 52 such that thebridge is in balance with zero voltage across its output terminals 51and 60, and hence zero voltage at the input terminals 42 and 63 of theamplifier 23. Now upon application of a load to be measured by the scalemechanism, the load cell network will develop a net voltage in one phasedirection and of a magnitude which is proportional to the weight of theimposed load. This voltage, hereinafter referred to as the net celloutput voltage, is transmitted through the tare bridge 20 and thebalance bridge 22, to provide a resultant voltage at the amplifier inputterminals 42 and 63, which voltage then is amplified and reflected inthe amplifier output circuit 64 as a control voltage. Such controlvoltage which is hereinafter referred to as the unbalance voltage of thescale system, is applied by the circuit 64 to the motor control winding66, to cause motor operation (assuming the motor main winding 68 to beenergized) in one direction such as to move the element 51 of thepotentiometer 52 in the direction to effect an unbalance of the balancebridge 22. When bridge 22 provides an opposing voltage equal to the netcell output voltage, the motor 24 stops because of the absence of aresultant input voltage to the amplifier at such time, with consequentzero voltage at the motor control field 66. When the load on the scaleplatform is removed in part or entirely, the net cell output voltage isreduced proportionately. The opposing voltage provided by balance bridge22 and the net cell output voltage becomes unbalanced but in theopposite direction, so that motor 24 in response to the changedunbalance voltage, operates the movable element 51 of the balancepotentiometer 52 in the opposite direction to decrease the opposingvoltage provided by bridge 22 until the opposing voltage and net celloutput voltage are balanced, at which time the motor again stops.

An important feature of the present system resides in the controlinstrumentality 30 associated with the balance bridge 22. It will beappreciated that by properly adjusting the balancing characteristics andrange of the balance bridge 22, the entire range of the rebalancingpotentiometer 52 may be made effective such as to encompass the wholeload range capacity of the platform scale mechanism with which thepresent electrical system is utilized. Further, in controlling thecharacteristics of the balance bridge 22, the present system may beadjusted or calibrated for providing indications of the weight of theloads to be measured in terms of units of any given measuring system, asthe pound units of the avoirdupois system. To this end, the control 30provides a resistance circuit comprising a control potentiometer 71 inseries in the conductor line 59 with a fixed resistance 72. By utilizinga resistance 72 having a predetermined resistance value, and adjustingthe total resistance of the resistance circuit through adjustment ofresistance 71, the voltage at the bridge input terminals may be therebydetermined and fixed at a potential value required for calibrating thebalance bridge network 22 so that it will be effective oversubstantially the entire range of the balancing potentiometer, todetermine at any scale loading within the maximum load range of thescale system, the extent of operation of motor 24 required to actuate(through reduction gear 25) potentiometer element 51 sufiiciently toproduce a zero error signal, such that the relation between the scaleload weight in terms of say, pounds, and then umber of revolutions orfractional part of a revolution of the motor rotor element is inaccordance with a definite desired ratio. The ratio thus determined maybe for example, 10:1, so that each ten revolutions of the motor rotorelement represents one pound of scale load weight. Consequently throughproper selection of the gear ratio in respect to the portion of thereduction gear unit 25 connecting motor 24 to the weight indicator 26,the latter may be adapted to provide in response to motor operationthereof, weight indications in pounds.

Included in the lead 65 of supply circuit 70 to the main field 68 ofmotor 24 is a control switch 78 which when closed, conditions the motor24 for operation in response to load responsive energization of itscontrol field winding 66, while in open position, it prevents motoroperation. Arranged preferably in the opposite lead 67 of circuit 70 isa cam-controlled switch 73 which as will appear more fully hereinafter,normally is in circuit-closed condition at all times other than duringcyclic operation of the recorder mechanism 29. Accordingly, at thispoint in the description the switch 73 may be considered as being inclosed condition. Thus, control switch 78 which is in the nature of amotor holding control, afiords in open position motor retention of aweight reading on the dial indicator 26 while the indicated load isremoved from the scale platform and another load placed thereon. Thesucceeding load will result in a corresponding unbalance voltage at themotor control winding 66, so that upon closure of switch 78, the motor24 will operate forwardly or reversely depending upon the phase of thevoltage at Winding 66, such as to relocate the indicator pointer in aposition corresponding to the weight of the new load. Such weightindication is effected quickly and in a much shorter time than would berequired were the motor returned to its initial zero load position inresponse to removal of the load from the scale, followed by actuation toset-up the indicator weight in accordance with the succeeding loadapplication. This feature is of particular advantage in instances wherea number of nearly similar loads are to be measured.

The system of Fig. 2 as thus far described, is essentially in accordancewith the subject matter as disclosed in the hereinbefore notedapplication Serial No. 259,148. However, in the system as now provided,the motor drive to the weight indicator 26 is utilized to set-up orcondition suitable weight printing or recording mechanism for producingprinted or other permanent recording of scale load weights. In additionand importantly to the present invention, weight printing or recordingby the recorder mechanism is so controlled by scale balance sensingmeans, that printing of load weight cannot occur until the scale is inexact balance.

With reference again to Fig. 2, any suitable, well known form ofrecording or printer mechanism may be employed herein, as for exampleprinter mechanism of the; character shown in Hadley et al. Patent2,070,011 to which reference may be had for structural and operationaldetails. For the purpose of present illustration, only such: partsthereof as are necessary to an understanding of the present invention,are shown diagrammatically in: broken lines in the recorder unitdesignated generally by the numeral 29. A plurality of stepped weightselectordiscs 90, 91 and 92 are fixed on a shaft 94 which is ro-- tatedcoincidentally with the shaft of the dial indicator 26 as the latter ismoved by the motor 24 through the, reduction gearing 25. While but threeselector discs 90,, 91 and 92 are shown, constituting respectively theunits, tens and hundreds selectors of the recorder, it is to beunderstood that one or more additional selector discs of higher order,as thousands, ten thousands, etc., may be: employed according to thecapacity of the scale.

Arranged for cooperation with the selector discs aretype setting racks95, 96 and 97 disposed respectively irn alignment with the discs 90, 91and 92 and movable into engagement with the disc steps by actuatingpinions 98 on a common drive shaft 100 which is rotated by the recorderoperating motor 101. Although not here shown, the pinion drive from theshaft 100 to each of the racks, is such as to permit displacements ofthe racks to the same or relatively diflerent extents until each abuts astepof. its selector disc; Further; the racks operate type sectors ortype bars (not shown) such that in accordance with the scale settingof'the selector discs, rack 95 in abutment with a step of units disc 90locates its type bar to present a units type numeral in printingposition, while rack 96 in abutment with a step of tens disc 91 locatesits type bar to present a tens type numeral in printing position, andsimilarly with respect to rack 97 inabutment with a step of hundredsdisc 92 locating its type bar to present a hundreds type numeral inprinting position. In the diagrammatic example shown, a printing hammer102 is cam-actuated from the shaft 100, as through the cam 104 efiectivein the cycle of printer operation at a point therein following printingpositionment of the several type bars, to produce a record of the scaleweight on a suitable tape, weight card or the like, interposed betweenthe hammer and type bars.

- Energization of the recorder motor 101 is from a supply circuitcomprising conductors 105 and 106 which may be connected to the 110volt, 60 cycle source 69. One terminal 108 of the motor is connected bya lead 109 to conductor 106, while the opposite motor terminal 110 isconnected by leads 112 and 113 to conductor 105. Lead 113 includesnormally open contacts 114 of an electro-magnetic energizing circuitcontrol relay 116 having its relay winding 117 connected across theconductors 105-106 through a recorder start push button switch 118. Foroperator convenience the switch 118 need be closed only momentarily toinitiate energization of the relay winding 117, as the latter then isretained in energized condition throughout the printing cycle, by aholding circuit comprising a cam-controlled recorder cycle switch 120,conductor 121 connected between relay winding 117 and switch 118 andextending to one terminal 122 of cycle switch 120, and conductor 124connecting the other cycle switch terminal 125 to the motor lead 113containing the contacts 114. The cycle switch cam 126 mounted on themotor operated shaft 100, has a single depression or notch 128 in itscircular periphery 129 of uniform radius, provided for reception of theswitch cam-follower 130 to effect open-circuiting of the cycle switchfrom its closed position maintained so long as the follower 130 ridesthe uniform radius extent of the cam periphery 129. Motor rotation ofshaft 100 is counter-clockwise as appears in Fig. 2, so that therelative positions of cam 126 and switch follower 130 as shown, arethose obtaining near the end of the recorder cycle as will appear morefully presently.

- Turning now to an important feature of the present invention,operation of the printer mechanism to eifect weight recording, is hereprevented until the scale system attains exact balance. As shown in Fig.2, included in the supply lead 112 to the printer operating motor 101 isthe switch portion 132 of an electro-magetic relay switch 133. Switch132 normally is in closed circuit position in the de-energized conditionof the relay winding 134, and is held open upon and during energizationof the relay winding. The relay coil 134 is supplied from a suitablesource of energizing potential (not shown), by a supply circuitincluding a grounded conductor 136 connected to one terminal of therelay coil 134, and a conductor 137 leading to the other terminal of thecoil. Included in conductor 137 is the switch portion 138 of adifferential electro-magnetic relay 140 having relay windings 142 and143, the relay being of a type wherein in the de-energized condition ofboth windings 142 and 143, the movable switch element 144 is normallydisposed in a neutral or switch-open position between the fixed contactelements 146 and 147 having common connection with the portion 148 ofconductor 137.

' The operation of relay 140 is controlled by a scale balance sensingdevice provided by a phase-sensitive electronic circuit indicatedgenerally at 150, which in the present example, is adapted and arrangedfor sensing the presence and absence of unbalance voltage in theamplifier output-circuit leading to the control field 66 of motor 24. Inso sensing, it responds to such unbalance voltage of eitherpositive ornegative phase, by causing operation of the differential relay such thatits movable switch' element 144 is in engagement with contact 146 orcontact 147, thereby closing the supply circuit to the winding 134 ofrelay 133 toenergize the latter and hold open the switch 132 to preventenergization of the recorder motor 101. Although here shown as connectedtothe amplifier output circuit 64, the device 150 may be connected in anintermediate stage of the amplifier, or to the amplifier input forresponse to the resultant voltage at that point.

The electronic control device 150 as illustrated in Fig. 2, comprises apair of'vacuum tubes which in the present example of the device may bethree-element tubes as the triodes 151 and 152, and includes an anodevoltage supply transformer 154 having primary winding 155 connected to asuitable source such as the 110 volt, 60 cycle line 156, and secondarywinding 158 the center point of which is tapped and grounded at 159.Anode 160 of triode 151 is connected by lead 162 to one end terminal oftransformer secondary 158, and similarly the anode 163 of triode 152 isconnected by lead 164 to the opposite end terminal of the transformersecondary 158. The respective cathodes165 and 166 of triodes 151 and 152are connected together through series-connected capacitances 167, withthe circuit connection between the capacitances grounded as at 168, andconnected by lead 170 to a conductor 171 which connects the adjacentends of the relay coils 142-and 143 in series-circuit relation. A lead172 connects the remaining end of relay coil 142 to the-cathode 165 oftriode 151, while lead 174 connects the remaining end of relay coil 143to the cathode 166 of triode 152. Extending from the control grid 175 oftriode 151 is a conductor 176, and leading from grid 178 of triode 152is a conductor 179, these conductors being connected together and to oneend of an unbalance voltage input lead 180, as at 182. The lead 180preferably including a suitable circuit coupling capacitance 183,extends to connection at 184, with one side of the amplifier outputcircuit 64. The opposite side of the latter circuit is grounded at 186,while bridging the circuit 64 is a suitable condenser 187. Included inthe grid circuit of the electronic relay circuit is a grid resister 173grounded as shown.

It will appear now from the foregoing description of the control 150,that the triodes 151 and 152 are in phase opposition in the circuitarrangement shown, and have their grid elements in a common inputcircuit coupling them to the amplifier unbalance voltage output circuit64 so that the grid voltage of each triode results from and variesdirectly with the unbalance voltages in the circuit 64. Consequently, inthe presence of unbalance voltage of one phase direction, the gridvoltage of one triode, say triode 151, will be in phase with the anodevoltage of such triode, and the grid voltage of the other triode 152will be out of phase with the anode voltage thereof.

- Therefore, current conductance will take place through triode 151 withresultant energization of the relay winding 142 and consequentcircuit-closure displacement of switch 144 to-engagement with contact146, while current conductance through triode 152 either will not appearor at most, will occur to a minimum or limited extent. When theunbalance voltage is of opposite phase, the reverse of the above willtake place, resulting in predominant energization of relay winding 143with resultant engagement of switch 144 with contact 147. Hence ineither case, the relay will be operated by engagement of relay switchelement 144 with one or the other of the contacts 146 and 147, tocomplete the supply circuit to relay coil 134 and thereby activate relay133 to effect an open-circuit condition of its switch 132. Thus, so longas there is unbalance voltage of either phase direction in circuit 64,the trrode sensing circuit will respond as described, to operate relay140 and thereby the relay 133, the latter responding to open and holdopen the supply circuit to the motor 101, to prevent recorder operation.When the unbalance voltage in circuit 64 becomes zero, indicative ofexact scale balance either in loaded or unloaded condition, the triodesensing circuit then becomes deactivated such as to result in a neutralor open-circuit position of the relay switch element 144, with attendantde-energization of relay 133 and consequent closure of its switch 132.Whereupon, operation of the recorder mechanism may take place.

In the present scale load sensing and weight indicating system,a'balanced condition of the system obtains when the voltage in circuit64 is zero. Nevertheless, at balance there may be a small residualvoltage in circuit 64, comprised mainly of quadrature and third harmonicvoltage components. Such residual voltage does not adversely atfect theattainment of true weight indication by the system, since the motor 24does not respond to small voltages of this character. The more sensitivetriode balance sensing circuit however, may and normally will respond tothese component voltages. But because of the opposed relation of thetriodes 151 and 152 in the circuit as shown and described, and due tothe nature of quadrature and third harmonic component voltages, bothtriodes will conduct if at all, in equal degree to effect equal butopposite energization of the differential relay windings 142 and 143. Asa result, the relay switch 144 will remain in its neutral oropen-circuit position.

In the operation of the system including the recorder mechanism andbalance sensing provision as shown by Fig. 2, the control motor 24 willbe in initial position in the absence of scale-applied load, to elfectthrough reduction gearing 25 zero-weight reading by the indicator 26 andangular disposition of the weight-selector discs 90, 91 and 92 ininitial positions corresponding to zero weight. As so conditioned,unbalance voltage will be absent in circuit 64, the triode balancesensing circuit will be in balance with the relay 140 in open-circuitcondition, and the relay 133 will be deenergized with its switch 132closed to complete the recorder motor supply lead 112. Now, uponoperator actuation of the push button switch 118, as by momentaryclosure thereof, the relay 116 thereby is energized to close itscontacts 114 in motor supply lead 113, with the relay retained inenergized condition through the holding circuit including the recordercycle control switch 120. While Fig. 2 shows the cam 126 in a positionof counter-clockwise rotation near the end of its rotationaldisplacement in the cycle, its initial position as at the start of thecycle, is such that the switch follower 130 engages the cam periphery129 in the region adjacent the cam notch 128. So long as the camfollower 130 is on the cam periphery 129, the switch 120 is therebyretained in closed condition. Consequently, at the start of the cyclewherein switch 120 is closed with its follower 130 on the cam peripheryat the point 190 thereof, the motor 101 then energized from the supplycircuit 105-106 through the closed relay contacts 114 and closed switch132, operates to rotate shaft 100 in the counter-clockwise direction,and with it the cam 126, pinions 98 and the print hammer actuating cam104. The pinions 98 displace the racks 95, 96 and 97 to engage: mentwith steps of the discs 90, 91 and 92 and since in the present examplethe latter are in initial or zero weight positions, each rack will abutthe zero weight step of its associated disc and thereby set itsassociated type sector or bar (not shown) for zero weight printing. Inthe revolution of the shaft 100 and following type setting by the racksand selector discs, cam 104 actuates print hammer 102 to effect printingor impressing of a tape or card against the type to record weight, aszero weight in this instance. Following the printing or recordingportion of the cycle, further rotation of the cam 126 brings the camnotch 128 to a position for reception 10 of the follower 130, the latterentering the notch and thereby opening the cycle switch 120. Immediatelycon sequent to opening of switch 120, the relay 116 becomes de-energizedwith its contacts 114 opening to de-energize the print motor 101. Motor101 then rapidly decelerates to a stopped condition, turning the cam 126a further angular distance sufiicient to elevate the follower 130 fromthe cam notch 128 and to the initial point of the cam, the switch 120thereby being again closed, ready for a succeeding printer cycle.

At this point it is to be noted in connection with recorder mechanism asherein diagrammatically indicated at 29, and as more completelydisclosed in the aforementioned Patent 2,070,011 to Hadley eta1.,provision is made to continue recorder operation throughout therecording cycle once the recorder motor 101 is energized and startsoperating. It is deemed suflicient in the present disclosure, toillustrate a relatively simple, yet effective arrangement exemplary of asuitable provision for this purpose which, as here showndiagrammatically in part, includes a second switch 191 which controls aholding circuit for motor 101, in bridging relation to the switch 132 asthrough conductors 193 and 194. Operation of switch 191 is controlled bya cam 198 on shaft 100, the cam having a raised part or nose 199 andbeing fixed on shaft 100 in a position relative to the position of cam126, such that the cam nose 199 is in axial alignment with the initialor start point 190 of cam 126. Engaging the cam 198 is a followerelement 203 of the switch 191. With this arrangement, when the cams 126and 198 are in initial positions, as with the follower 203 on the nose199 of cam 198, the switch 191 will be in open-circuit condition,opening the shunt circuit of conductors 193 and 194. Upon starting ofrecorder motor 101, the cam nose 199 passes from under follower 203 andthe latter then rides on the surface of the cam with the contacts ofswitch 191 in closed condition. The closed position of the switch 191completes the bridging circuit about switch 132, so that the motor 101will continue operation throughout the recorder cycle and independentlyof the position of switch 132.

In addition to the shunt switch 191 provided to assure recorderoperation through its recording cycle and independently of controlswitch 132 once the recorder motor 101 is energized, the presentcontrols include the hereinbefore mentioned switch 73. The function ofthis switch is to open the power supply lead 67 to the main winding 68of motor 24 and to retain the circuit open throughout each cycle ofrecorder operation. Thus, during each operation of the recordermechanism to effect weight recording, motor 24 is thereby efiectivelyprecluded from operation in response to changes in scale loading orother factors producing change in the unbalance voltage condition incircuit 64, so that it cannot then attempt to alter the set positions ofthe selector discs 90, 91 and 92 (as well as the position of theindicator 26) while the recorder is undergoing its recording cycle.Operational timing of switch 73 to accomplish the above purpose, may beaffected through cam-control thereof, as by the cam 74 fixed on recordershaft 100 and having a raised portion or nose 75. Similarly to earn 198,the cam 74 is located so that its nose 75 is in axial alignment with therecorder cycle start point 190 of the cycle switch cam 126. In thatrelation and with the cams disposed at the start position of therecorder cycle (hereinbefore described), the camfollower element 76associated with the movable element 77 of switch 73, will be on the camnose 75 and thereby elevated to close the contacts of the switch.Consequently, so long as the recorder mechanism is not in recordingoperation, the switch 73 will be and remain in circuit-elosed condition.But upon recorder operation, the cam nose 75 passing beyond the follower76, results in displacement of the switch element 77 to effectopencircuiting of the switch, with the latter again closed by thecamnose 75 at the end of the recorder cycle.

Continuing with the description of operation, upon loading: of thescale, the system responds as hereinbefore described,,to actuatetheindicator 26 to a position indicating the weight of thescale load,and at the same time to actuate the printer selector discs 90, 91 and 92to positions corresponding to the load weight. Now if the printer startswitch 118 be operated, the relay 116 will close its contacts 114 andhold through closed switch 120, and should the switch 132 then be inclosed position, the print motor 101 will operate the printing mechanismthrough its printing cycle to produce a record of the scale load weight.However, if the scale system is not then in balance, the triode circuitsensing unbalance voltage in the circuit 64, will operate to cause anopen circuit condition at switch 132. The latter then will not closeuntil zero unbalance voltage obtains in circuit .64, at which time thescale system will be in exact balance.

The foregoing description of operation of the system is predicated upona closed position of the motor holding switch 78. However, when thisswitch is opened to hold the motor 24 in operated position with theindicator 26 at a weight reading corresponding to the weight of a givenscale applied load, so long as such given load remains on the scaleplatform the system will remain in balance, and the print cycle may berepeated as often as desired, each time producing a record of the givenweight. Now, if the given weight be removed from the scale while themotor 24 is in held condition (switch 78 open), the motor positionedindicator 26 will remain at the weight reading of the given weight, butoperation of the recorder mechanism cannot take place upon closure ofthe printer start switch 118, because control switch 132 then will beopen. The open condition of switch 132 in this instance, is the resultof unbalance voltage in the circuit 64 to the removal of the givenweight and consequent unbalance of the network system. Such voltage issensed by the triode circuit 150, with the result that relay 138 isclosed to energize relay 133, and the latter then holding open itsswitch 132. If now the switch 78 be closed, motor 24 will respond tosuch unbalance voltage by restoring the balance of the network systemcorresponding to zero loading of the scale, and coincidentally therewithreturning indicator 26 to zero reading and restoring the selector discs90, 91 and 92 to initial or zero weight positions. Whereupon therecorder mechanism may be operated to provide a record of Zero weight,since in the balanced condition of the system then obtaining, the switch132 will be closed.

Returning to the first mentioned condition, as with switch 78 open tohold the indication of the given weight referred to, upon removal ofsuch weight and application of a different weight to the scale, thenetwork system re,- sponds by producing unbalance voltage in circuit 64,of a value corresponding to the net weight. Again, so long as the switch7 8 remains open, the voltage in circuit 64 results through the 'triodesensing circuit 150, in an open-circuit condition of switch 132 toprevent operation of the recorder mechanism. However, upon closure ofswitch 78, motor 24 will. respond by operation to balance the networksystem, to operate the indicator 26 to a position indicative of the newweight, and to set the selector discs 90, 91 and 92 according to the newweight. Whereupon, closure of the start switch 118 will causerecorderoperation if switch 132 is then closed, or condition the recorder foroperation automatically upon closure of switch 132 in response tosensing of scale balance by the triode circuit 150.

In the system according to Fig. 2, the power supply at 69, at theprimary of transformer 19, at primary 155 of transformer 154 and to thepower input (not shown) of the amplifier 23, are provided from a singlepower source common to the indicated power inputs. Moreover, while thesystem shown preferably is intended for operation on 110, 60 cyclepowersupply, it may. readily be'adapted to a power supply suitable forthe purpose and of. a

voltage and frequencyothenthan as herein indicated. It will beappreciated that by-energizing the several com} ponents of the systemfrom one'and'the same power source,-maintenance of required phaserelationships inthe system is assured,-and the system is therebyrenderedselfcompensating for normally encountered variations in thesupply voltage. I 1

Since the response of the present system is quite rapid in weighingoperations, under certain weighing conditions as for example, when thescale platform mechanismis subjected to vibratory movements of momentaryor longer durations, or in the event the applied load should be reducedbefore the system comes to balance, the unbalance voltage in the circuit64 will undergo consequent phase reversals. Such phase reversals of theunbalance voltage result not only in corresponding reversing or socalledhunting operations of the motor 24 in its attempts to re-balance thebridge network 22, but in movements of the differential relay switchelement 144 from one to the other of the contacts 146 and 147,consequent to unbalance voltage response of the electronic relay circuit150. Each time the relay switch 144 moves from one contact to the other,the energizing circuit 136-137 to the relay 133 is broken, withresultant closure of the recorder motor control switch 132, andoperation of recorder motor 101 should the contacts 114 be thenclosed.

In order to prevent such momentary de-energizations of the relay 133during reversals of contact operation of the relay 140 consequent tophase reversals of the unbalance voltage in circuit 64, the presentsystem includes a suitable time delay device in operative connectionwith the relay 133 and eflective for continuing energization of thelatter while the differential relay switch element 144 is in movementfrom one fixed contact to the other under the hunting condition'asaforesaid. A simple device for this purpose, is provided by a suitablecapacitance 207 of predetermined capacity value, arranged in parallelwith the relay winding 134 as across the supply conductors 136 and 137.

Except for certain additional control provisions now to be described,the system as shown in Fig. 3 is similar to that of Fig. 2. Accordingly,the circuits and circuit elements appearing in Fig. 3 whichcorrespond'to the like circuits and elements shown in Fig. 2, are heredesignated by the same reference numerals. The additional controlprovisions now to be described, areprovided to adapt the arrangementaccording to Fig. 2, for operational control from the operator-actuatedprinter push button switch means under conditions when it is desirableto leave the motor hold switch 78 in open position, as when a series orrelatively large number of items of somewhat similar weights are tobeweighed and it is not desired to have the system returned tozerobalance before each succeeding item is applied to the scale.

Referring to Fig. 3, in bridging relation to the motor hold switch 78(here shown as, a normally open push button switch) is a contact circuit200 having therein normally open contacts 201 of an electro-magneticrelay 202. The relay winding 204 is adapted for energization from thesupply circuit 106 through push button switch 205 between one end of thewinding and the supply conductor 105, and switch 206 between theopposite winding end and the supply conductor 106. Switch 205 is joinedwith switch 118 for simultaneous manual closure, it being understoodthat these switches are normally urged to open positions. A holdingcircuit 208 isprovided for the relay 202, such circuit including thenormally open contacts 209 which areclosed upon energi- Zation of relaywinding 204. 1

Switch 206 is operated by the relay 133, and includes movable switchelement 210 normally urged to a switchopen position relative to fixedswitch contact 212 when relay 133 is de-energized.

In operation of the system utilizing the additional controls and withthe motor. holding .switch 78. retained in open position, uponapplication of load to the scale, the network system responds byproducing in the circuit 64 an unbalance voltage as before described.Since switch 78 is open, motor 24 does not operate, but the triodebalance sensing circuit 150 responds to the unbalance voltage byactuation of the relay 140 to engage switch element 144 with one or theother of the fixed contacts 146 and 147. As hereinbefore explained,closure of switch 138 produces an energized condition of the relay 133such that it holds open its switch 132 to prevent recorder operation,and at the same time effects closure of contact 210 with contact 212.With the system so conditioned, manual closure of switch 205 (andcoincidentally switch 118) then results in energization of relay winding204 and consequent closure of relay holding contacts 209, withsimultaneous closure of contacts 201 to complete the circuit 200bridging the open hold switch 78. Closure of switch 118 operates therelay 116 to close the contacts 114, the relay remaining energizedthrough its hold circuit including the cycle switch 120, upon release ofswitch 118. With switch 210 closed and upon release of switch 205, relay202 remains energized through its hold contacts 209, to retain contacts201 closed.

Upon closure of the bridging circuit contacts 201, motor 24 immediatelyresponds to the unbalance voltage in circuit 64 by operation to balancethe network system, and at the same time to move the indicator 26 to aposition indicating the weight of the scale load, and to set the printerselector discs 90, 91 and 92 in positions corresponding to the loadweight. When the system becomes balanced with zero voltage at thecircuit 64, the triode balance sensing circuit 150 responds byde-energization of the relay 140, whereupon switch 138 returns toneutral or circuit-open position. The resultant deenergization of relay133, delayed momentarily by the time-delay capacitance 207, causes opencircuiting of the switch 210 which causes de-energization of relay 202with consequent opening of the holding contacts 209 and bridge circuitcontacts 201. With contacts 201 open, the motor 24 is then retained inload balanced position to hold the weight reading on indicator 26 and toretain the selector discs 90, 91 and 92 in actuated positionscorresponding to the load weight. The de-energization of the relay 133of course, effects closure of switch 132, whereupon the motor 101operates to drive the recorder mechanism through the recording orprinting cycle, as before described.

The weight of the load thus having been indicated and recorded, suchload now may be replaced by the next item to be weighed. At such timeand before the manual switches 205 and 118 are closed, the weight of thepreceding load item will remain on the indictor 26, while the printerselector discs will be in positions corresponding to such load. Now, bymomentarily closing switches 205 and 118, the system will respond byoperation through the indicating and printing cycle as above described,such as to indicate the new weight on indicator 26 and effect printingof the new weight. The cycle is repeated for each succeeding load item,and it will be now appreciated that in each case, the extent ofoperation of motor 24 required to re-balance the network and to actuatethe indicator and set the printer selector discs, is determined by thedifference in weight of the item undergoing weighing and of theimmediately preceding. item. Thus, the added control provisions whenutilized, greatly facilitate rapid weighing of a plurality of similar,weight load items weighed one at a time, since in this instance thesystem does not return to zero weight balance between weighingoperations.

Fig. 4 illustrates a modified form of triode balance sensing circuitwhich may be substituted for that embodied in the system according toFigs. 2 and 3. This circuit is approximately as sensitive and effectiveas the first described circuit, and is adapted for controlling a singlecoil relay switch instead of a differential relay. As in the firstembodiment, a pair of triodes 300 are provided, with the anode 302 oftriode 300 connected to one end of transformer secondary 304 having itscenter point tapped at 305 and grounded, and the anode 306 of triode 301connected to the opposite end of transformer secondary 304. Therespective grids 308 and 309 of the triodes 300' and 301 are connectedtogether and to the unbalance voltage input coupling circuit 310 whichleads to connection with the amplifier output circuit 64 (Fig. 2 forexample), with the grid circuit including a grounded grid resistor 311.Cathode 312 of triode 300 is connected to a resistance 313 and to oneend of winding 314 of the single coil relay switch 315, while thecathode 316 of triode 301 is connected to a like resistance 317 and tothe other end of relay winding 314. Moreover, resistances 313 and 317are connected in series with the mid-point 318 of the series connectiongrounded at 319, while the relay winding is bridged by a suitablecapacitance 320. Thus it will appear that the cathodes 312 and 316 areconnected in series by an impedance circuit provided by the resistances313 and 317 and having a mid-point terminal 318 in ground circuitconnection to the center tap 305 of the transformer secondary 304.

In operation, when the grid voltage of triode 300 (due to unbalancevoltage input thereto) is in phase with the anode voltage thereof, thetriode will conduct to produce a voltage drop across the resistance 313.In this instance, the grid voltage of triode 301 will be out of phasewith the anode voltage, to result in little if any voltage drop acrossresistance 317. The result is a potential difference across relaywinding 314, which energizes the relay to switch closed position of itsswitch element 321, the switch of course, controlling the supply line137 to relay 133 (Fig. 2). Conversely, when the grid voltage of triode301 is in phase with the anode voltage of such triode, the latter willconduct to produce a voltage drop across resistance 317, thus resultingin a potential difference across relay winding 314 and causing relayactuation to close its switch 321.

Fig. 5 illustrates a triode balance sensing circuit like that of Fig. 4but modified to provide for greater sensitivity of circuit response. Forconvenience of disclosure, the elements of this circuit corresponding tothose in the circuit of Fig. 4, are here given the same referencenumerals. As shown, the cathode resistance 324 connected to cathode 312of triode 300, is tapped at 325 with the tap connected through aresistance 326 to the grid circuit 328 of triode 300. Similarly, theresistance 329 connected to cathode 316 of triode 301, is tapped at 330with such tap connected through a resistance 332 of equal value withresistance 326, to the grid circuit 333 of triode 301. Each grid circuitincludes a coupling capacitance 334.

Fig. 6 shows another balance sensing circuit capable of use in thesystems of Figs. 2 and 3, and which employs but a single triode, as thetriode 340. The anode 341 of the triode is connected by lead 342 to oneend of the winding 344 of a single coil relay switch 345, while thecathode 346 is in a ground circuit 348 including an adjustableresistance 349. The remaining end of relay winding 344 is connected by alead 350 to the positive side of a suitable source of direct current, asthe battery 352 here shown by way of example only, the negative side ofthe source being grounded at 353 in return-circuit connection to thecathode 346 through the grounded cathode circuit 348. Unbalance voltageinput to the triode grid element 354, as from the circuit 64 (Figs. 2and 3), is effected by a coupling circuit including conductor 356leading from circuit 64 and connected to one side of a suitablerectifier 357, a suitable coupling capacitance 358 being interposed inthe conductor. The other side of the rectifier is connected by aconductor 360, to the grid 354. Completing the coupling circuit whichofcourse includesjaground returncircuit, area resistance ground circuit361 including resistanceelement 362, and a ground CiICllltQ36 4including resistance 365 andcapacitance 366 in parallel relation asshown. Unbalance voltage input to thesensing circuit, is rectified bythe rectifier 357 and applied to the triode grid element 354, causingcurrent flow through'the triode to energize the relay-winding 344 withresultant closure of its switch 345. When the unbalance voltage appliedto the grid 354 decreases to zero at scalebalance, current conductanceof the triode normally reduces to a value resulting in de-energizationof the relay winding 344 and opencircuiting of its switch 345. 7.

Having now described by illustrations and description, several presentlypreferred embodiments of the invention, including several ditferentbalancesensing circuits suitable for embodiment therein, what we desireto claim and secure by Letters Patent is;

1, In a weighing scale system, means for sensing scale loading andproducing a voltage the-magnitude of which is proportional to the weightof a scale load, an electric motor having a control winding and operablein response to energization of said control winding, electrical meansfor translating said voltage to an unbalance voltage at said controlwinding for causing motor operation, said electrical means including abalancing network having a control device operable ;by said motor foreffecting a balanced condition of the network to counterbalance theunbalance voltageat the motor control winding and thereby to de-energizesaid winding, said network being adapted for determining the extent ofmotor operation required to effect said unbalance voltagecounter-balancing condition of the network, such that it is proportionalto the weight of a scale load, weight recording mechanism includingsettable weight control means and motor means for actuation of themechanism to effect weight recording in accordance with the setting ofthe control means, means actuated by said motor for setting saidsettable weight control means in accordance with the weight of a scaleload, an energizing circuit for said motor means and including a circuitcontrol switch, electrical means for sensing the presence and absence ofunbalance voltage at said motor control winding, and means responsive tothe last said means sensing zero unbalance voltage at said controlwinding, for causing closure of said circuit control switch to completethe energizing circuit to said motor means. 7

2. In a weighing scale system, an electric motor having a controlwinding for efiecting operation of the motor only upon and duringexcitation of the winding, means for sensing scale loading and producingan unbalance voltage at said motor control winding, said means includinga voltage counter-balancing electrical network having a network balanceadjusting device actuated from said motor, said network being effectivethrough motor operation of said device in response to unbalance voltageexcitation of said motor control winding, to reduce the unbalancevoltage to zero with consequent cessation of motor operation, saidbalancing network being adapted for determining the extent of motoroperation required for actuation of said balance adjusting device toefiect network reduction of the unbalance voltage to zero, such that itis in predetermined proportion to the weight of the scale load, weightrecording mechanism including settable control means and motor means foroperating the mechanism to efiect weight recording in accordance withthe setting of said control means, means operatively connecting saidmotor to said control means for motor actuation thereof to a settingcorresponding to the weight of the scale load, an energizing circuit forsaid motor means, an electronic network for sensing the presence andabsence of unbalance voltage at said motor control winding,.and meansresponsive to said electronic network for rendering said energizingcircuit inefiective to energize idmc me ns dur a c e k Sen n t h Pr e eof unbalance voltage atsaid. ,motor control winding. n 3. In a weighingscale-system, an electric motor having a motor operation controlwinding, means for sensing scale loading and producing in application tosaid control winding, an energizing unbalance voltage for causing motoroperation, said means including balance network means effective inresponse to operation of said motor, for reducing the unbalance voltageat said control winding to zero voltage and thereby effect cessation ofmotor operation with the motor actuated to an extent proportional to theweight of the scale load, weight recorder mechanismincluding settablecontrol means operable by said motor to a setting corresponding to theweight of the scale load; and means actuatable for effectinginaccordance with the setting of the said control means, a record of thescale load weight, an operating motor for the last said means, anenergizing circuit for said operating motor includinga circuit controlswitch, an electronic circuit coupled to the first said means forsensing unbalance voltage in application to said control winding, andmeans responsive to said electronic circuit for retaining said controlswitch in open-circuit condition so long as the electronic circuitsenses the presence ofunbalance voltage in application to. said controlwinding. I

4. In a weighing scale system, a weight recorder having settable controlmeans and recording means operable in accordance with the setting of thecontrol means, motor means for operating the recording means, anelectric motor in operative connection with said settable controlmeans,.said electric motor including main and control windings, anenergizing circuit for the main winding including a control switchtherein, means for sensing scale loading and producing an energizingunbalance voltage at said control winding, said motor responding theretoupon energization of said main winding through closure of said controlswitch, by operation to an extent proportional to the weight of thescale load and thereby operating said settable control means to asetting corresponding to the scale load weight, said control switch incircuit-open position preventing operation of said electric motor,normally open switch means in parallel with said control switch,operating means including an electronic circuit coupled to said scaleload sensing means and responsive to unbalance voltage applied to saidmotor control winding, for efiecting closure of said switch means andenergization of said motor main winding to effect operation of saidelectric motor, and means for energizing said recorder motor means tocause operation thereof, said last means including a switch controlledby said operating means and movable to closed position upon response ofsaid electronic circuit to zero unbalance voltage at said controlwinding.

5. In a weighing scale system, an electric motor having a main windingand a control winding and operable only upon energization of bothwindings, an energizing circuit for said main winding including normallyopen contacts therein, means for sensing scale loading and producing atsaid control winding an unbalance voltage, said means including anelectrical network having a network balancing device operable by saidmotor for balancing the network to reduce the unbalance voltage at saidcontrol winding to zero voltageand thereby cause cessation of motoroperation, said network being adapted for determining the extent ofmotor operation required to balance the network and reduce the unbalanceoltage to zero value, such that it is in direct proportion'to the weightof the scale load, a weight recorder having settable control means andincluding recording means operable in accordance with the setting ofsaid control means, an, operating connection between said motor and saidsettable control means for motor operation of the latter to a settingcorresponding to the weight of the scale load, motor means for actuatingthe recording means to effect according to 17 a the setting of thecontrol means, a record of the scale load weight, an energizing circuitfor said motor means including a control switch normally urged to acircuitclosed position, electronic relay circuit means coupled to thefirst said means for sensing the presence and absence of unbalancevoltage at said motor control winding, said relay circuit means beingresponsive to unbalance voltage at the motor control winding to open andretain said control switch in open-circuit position, thereby to preventoperation of said recorder motor means, and conversely, responding tozero unbalance voltage at the control winding such as to permit returnof the control switch to circuitclosed position, and means controlled bysaid electronic relay circuit means for elfecting closure of saidcontacts in said main winding energizing circuit upon response of therelay circuit to unbalance voltage at said motor control winding,thereby to cause operation of said electric motor, the last said meansconsequent to response of said relay circuit means to zero unbalancevoltage at said control winding, causing return of said contacts tocircuitopen position with resultant de-energization of said main windingof the electric motor.

6. In a weighing scale system, a weight recorder including settablecontrol means, means including electric network means for sensing scaleloading and producing an unbalance voltage, the network means includinga motor responsive to said unbalance voltage for effecting a setting ofsaid recorder control means corresponding to the weight of the scaleload and coincidentally therewith, for affecting the network means suchas to reduce the unbalance voltage to zero value, said motor having amain winding, an energizing circuit for said winding having normallyopen contacts therein, motor means for operating said recorder toproduce a record of the scale load weight according to the setting ofsaid recorder control means, an energizing circuit for said motor meansincluding a normally closed switch therein, and relay means including anelectronic relay circuit coupled to said network means for sensing thepresence and absence of unbalance voltage therein, operable in responseto sensing of unbalance voltage by said relay circuit, to effect closureof said contacts and opening of said switch, thereby to efiectenergization of said motor winding for motor operation and to preventoperation of said recorder motor means, said relay means operatingresponsively to zero unbalance voltage sensing by the electronic relaycircuit thereof, to effect an opening of said contacts and to causeclosure of said switch, thereby to de-energize the motor winding andcause operation of the recorder motor means for operating the recorderto produce a record of the scale load weight.

7. In a weighing scale system, means for sensing scale loading andproducing a voltage the magnitude of which is proportional to the weightof a load applied to the scale, an electric motor having a controlwinding and operable responsively to energization of said controlwinding, electrical means for translating said voltage to an unbalancevoltage at said motor control winding to energize it, said electricalmeans including balancing network means having a balance control deviceoperable by said motor to a network balanced condition reducing theunbalance voltage at the motor control winding to a zero value, wherebyto de-energize said motor control winding, said network means therebydetermining the extent of motor operation such that it is inpredetermined di rect proportion to the weight of the scale appliedload, weight recorder mechanism including settable control means andmotor means for actuation of the mechanism to effect weight recording inaccordance with the setting of the control means, an operatingconnection between said electric motor and said settable control meansfor motor setting of the latter in accordance with the weight of thescale load, an energizing circuit including a control switch for causingoperation of said motor means to ac- 18. tuate said mechanism and efiectrecording of the scale load weight, electrical control means effectiveresponsively to and during unbalance voltage energization of said motorcontrol winding, for retaining said control switch in open position torender the energizing circuit ineffective to cause operation of saidmotor means, said control switch being movable to closed position uponoperation of said electrical control means responsively to reduction ofthe unbalance voltage to zero value, and means conditioning said controlswitch for delayed movement to closed position.

8. In a weighing scale system, a motor having a control winding, meansfor sensing scale loading and producing an unbalance voltage inapplication to said control winding for causing motor operation, saidmeans including a balanceable network having a balancing device operableby said motor to balance the network and thereby reduce said unbalancevoltage to zero value, said network being adapted for determining theextent of motor operation required to balance the network and reduce theunbalance voltage to zero value, such that it is directly proportionalto the weight of the scale load, a weight recorder including settablecontrol means, an operating connection between said motor and settablecontrol means for motor operation of the control means to a settingcorresponding to the weight of the scale load, motor means for operatingthe recorder to produce according to the setting of said settablecontrol means, a record of the scale load weight, an energizing circuitfor said motor means, an electromagnetic switch in control of saidcircuit, electronic relay control means sensing the presence and absenceof unbalance voltage in application to said motor control winding, andeffective in response to the presence of unbalance voltage at thecontrol winding to cause operation of the electromagnetic switch tocircuit-open position for preventing operation of the recorder motormeans, and means for delaying operation of the electromagnetic switch tocircuit-closed position responsively to said electronic relay controlmeans sensing the absence of unbalance voltage at the motor controlwinding.

9. In a weighing scale system, a motor having a control winding, meansfor sensing scale loading and producing an unbalance voltage inapplication to said control winding for causing motor operation, saidmeans including a balanceable network having a balancing device operableby said motor to balance the network and thereby reduce said unbalancevoltage to zero value, said network being adapted for determining theextent of motor operation required to balance the network and reduce theunbalance voltage to zero value, such that it is directly proportionalto the weight of the scale load, a weight recorder including settablecontrol means, an operating connection between said motor and settablecontrol means for motor operation of the control means to a settingcorresponding to the weight of the scale load, motor means for operatingthe recorder to produce ac cording to the setting of said settablecontrol means, a record of the scale load weight, an energizing circuitfor said motor means, an electromagnetic switch in control of saidcircuit, electronic relay control means sensing the presence and absenceof unbalance voltage in application to said motor control winding, andeffective in response to the presence of unbalance voltage at thecontrol winding to cause operation of the electromagnetic switch tocircuit-open position for preventing operation of the recorder motormeans, and means including a condenser connected in parallel with saidelectromagnetic switch for delaying operation of the electromagneticswitch in circuit-closed position responsively to said electronic relaycontrol means sensing the absence of unbalance voltage at the motorcontrol winding.

(References on following page) mamas,

, SIATES; BATENIS;

Messiter July 21, 1914 Bryce .1--. ..;1 Aug, 19, 19.30 Berger Mar. 31',1936 Brendel May 12, 1936 Orling Jan. 19, 1937 Hadley- Feb. 9, 1937'Haege1e June 15, 1937' Rauch Dec. 7, 1937 Basquin Ian. 23, 1940 CooperJan. 1;, 1946 Bore11 ,1 a Oct. 10, 1950 Erick 1. i -1 Nov. 1, 1950 July,24,1951

Siderman June 10, 19,5 2 e e-q v- -..--1S p. 9 4 s e e m :121", S m- 6,1.952 Blakes lee; .q Feb. 10,, 1953

